This invention relates generally to semiconductor structures and devices and to a method for their fabrication, and more specifically to semiconductor structures and devices and to the fabrication and use of semiconductor structures, devices, and integrated circuits that include a monocrystalline perovskite oxide layer.
Semiconductor devices often include multiple layers of conductive, insulating, and semiconductive layers. Often, the desirable properties of such layers improve with the crystallinity of the layer. For example, the electron mobility and band gap of semiconductive layers improves as the crystallinity of the layer increases. Similarly, the free electron concentration of conductive layers and the electron charge displacement and electron energy recoverability of insulative or dielectric films improves as the crystallinity of these layers increases.
Perovskite oxides have been grown over oxide substrates such as strontium titanate (SrTiO3), lanthanum aluminate (LaAlO3) and magnesium oxide (MgO), and more recently over silicon wafers using molecular beam epitaxy (MBE) techniques. Such techniques generally include depositing the oxide onto the substrate surface using one-layer-at-a-time or layer-by-layer shutter deposition techniques. The one-layer-at-a-time or layer-by-layer method is relatively slow because only constituents required to form a single layer are exposed to a substrate at any one time, while the constituents for the next layer are prevented from arriving at the substrate surface using shutters placed between the source and the substrate.
During the growth of the oxide film, a prior-art reflection high energy electron diffraction (RHEED) technique may be used to monitor the crystalline quality and the growth rate of the oxide film by evaluating the characteristics of the RHEED features and the intensity oscillations of a primary reflection spot. This technique generally requires that a substrate remain stationary during RHEED intensity oscillation analysis and consequently remain stationary during film deposition. Generally, film uniformity increases across a substrate if the substrate is rotated during the formation of the film.
Accordingly, a need exists for a technique to form monocrystalline perovskite oxides overlying a substrate that allows for real-time measurement of characteristics of the film, while the substrate moves relative to an analysis tool and for a method to grow the film by allowing multiple source shutters to be simultaneously open during a deposition process.